Abstract

In the present study, the optimum adsorption conditions for the uptake of methylene blue (MB) and reactive orange 16 (RO16) in binary dye solution by ethylenediamine tetraacidic acid (EDTA) modified rice hulls was studied. By using the Plackett-Burman design, the significant variables in affecting the MB and RO16 uptake in binary dye solution were identified as pH and contact time. The combined effects of interaction between the variables were determined using response surface methodology (RSM). The model predicted that at optimum conditions: pH 6.77 and contact time of 205.58 min, the MB uptake greater than 95% could be obtained. As for RO16, the RSM indicated that pH 3.17 and contact time of 205.59 min were optimal for maximum percent dye uptake. These predicted values were also experimentally validated to confirm the reliability of the models.

Key words: EDTA modified rice hulls, methylene blue, reactive orange 16, plackett burman, response surface methodology, optimization.